Hi All!

I ran into a memory leak in a system I'm working on, and I narrowed it down to a problem when using "goto &subroutine" for tail recursion. Here is a simple script that recreates the problem: 

#!/usr/bin/perl
use strict;
use warnings;

bar();

sub bar {
    if ( foo() ) {
        goto &bar;
    }
    return;
}

my $i = 0;
sub foo {
    return $i++ < 1_000_000_000;
}

[download]
This script quickly leaks memory, but if I just move the contents of foo() into the if conditional, it doesn't leak at all. Also, if I move the call to foo() before the conditional it doesn't leak.

The stack and all lexical variables should be deallocated when goto is called, right? I think something strange is happening with the memory used for the return value of foo() when it is called in the conditional block. Any ideas?

Thanks,
Justin

In reply to memory leak when using tail recursion? by juddhuck

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.